1. Field of the Invention
This invention relates in general to a microwave phase shifter element with a microstrip type structure and capable of being integrated into a network antenna. This structure comprises a ground conductor plate, a superposed dielectric plate substantially parallel to the conductor plate, and a conductor strip carried by a major face of the dielectric plate.
2. Description of the Prior Art
Such known phase shifters are ferrite phase shifters including a ferrite plate between the conductor and dielectric plates. The merit of the ferrite microstrip phase shifter is that it can be integrated into a hybrid microelectronic network antenna.
Nevertheless, a ferrite microstrip phase shifter offers somewhat limited performance. The drawbacks of a ferrite phase shifter are basically as follows:
relatively high insertion losses, typically higher than 1 dB for an operating frequency of approximately 10 GHz to obtain a 360.degree. phase shift; PA1 relatively high power requirement, in the region of a few hundred milliwatts; PA1 limited use in frequency, typically frequencies less than approximately 20 GHz; PA1 the need to correct the current control law when the operating temperature varies, owing to the temperature sensitivity of the magnetic features of the ferrite; and PA1 relatively limited peak power holding to avoid an increase in the insertion losses of the phase shifter. PA1 Fully reciprocal phase shifting thus suited to transmit/receive applications; PA1 Radioelectric performances better than any other type of phase shifter; PA1 Very wide frequency band; in fact the phase shifter element operates in TEM mode and in principle has no cutoff frequency; towards the high frequency ranges, the phase shifter element can include means for reducing radiation losses so as to form a high performance structure of suspended dielectric "strip line" type; the phase shifter element can be used up to 150 GHz and above; PA1 In principle, fairly insensitive to temperature; in fact piezoelectric materials are available whose d.sub.33 load coefficient remains constant throughout a broad temperature range; PA1 Control power, in the case of a phase shifter element including moving piezoelectric means practically zero in steady state, relatively low in switched state; PA1 Microelectronic structure well suited to the hybrid integrated circuit; PA1 Simple to use: PA1 Reduced size, compatible with applications relative to a two-plane electronic scanning network antenna.